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%I #8 Mar 30 2012 17:30:37
%S 0,4,18,45,864
%N (product of digits of n) * (sum of digits of n) = 4n.
%C A d-digit number is at least 10^(d-1), its product of digits is at most 9^d, and its sum of digits is at most 9d. For d >= 70, 4 * 10^(d-1) > 9^d * 9d, and so the sequence is finite. (Of course this can be improved.)
%t Do[ If[ 4n == Apply[ Times, IntegerDigits[n]] Apply[ Plus, IntegerDigits[n]], Print[n]], {n, 0, 10^7} ]
%K nonn,base,fini
%O 1,2
%A _Robert G. Wilson v_, Dec 13 2001
%E OFFSET changed from 0,2 to 1,2 by _Harry J. Smith_, Feb 03 2010